How can i install Blender 2.8 in ubuntu 18.4 with only console?
Installing from repositories is not recommended, they are hardly ever up-to-date.

Blender doesn't need to be "installed".

From a command line use wget.

wget "https://www.blender.org/download/Blender2.82/blender-2.82a-linux64.tar.xz/"


(or whatever is the link to the current version)

Then untar (uncompress) the resulting  file, and move the newly created blender folder to your home directory or a location that is convenient for you. From within the blender folder run the blender executable.

To use blender as a global command from the terminal, add the path of the blender executable to your path environment variable.